1. Field of the Invention
The present invention relates to a low voltage DC-DC converter (LDC) for a vehicle, and more particularly, to a technology for preventing an LDC from being overheated.
2. Discussion of Related Art
Electric vehicles of today, such as hybrid electric vehicles (HEV), fuel cell electric vehicles, and fuel cell hybrid vehicles, each are provided with a low voltage DC/DC converter (LDC) that serves as an alternator of a general gasoline vehicle. The low voltage DC/DC converter converts a high voltage (for example, 144 V, DC) of energy regenerated by a main battery or a driving motor to a low voltage 12 V (DC), and charges an auxiliary battery with the converted voltage or supplies power to electronic apparatus loads.
In order to extend lifespans of input/output batteries and ensure stable operations of electronic components using the batteries (a head lamp, an audio system and various electronic control units), it is important to keep a low voltage DC-DC converter in operation.
Meanwhile, when an LDC is overheated due to overload under the condition in which an additional cooling fan or a forced air cooling providing coolant are not available, the conventional converter control apparatus forcedly stops an operation of the LDC to lower the heat release temperature of the LDC. However, if the operation of the LDC is forcedly stopped due to overheat, the battery of 12 V is not stably charged, which degrades the reliability of the whole motor system of the vehicle.